UN Secretary-General Ban Ki-moon announced on Monday the appointment of Nobel Peace Prize Laureate Wangari Muta Maathai as UN Messenger of Peace on climate change issues.

"Professor Maathai's long record of achievement in environmental conservation and sustainable development makes her an excellent choice," Ban told reporters at UN Headquarters in New York at a press conference.

The secretary-general, who is leaving for Copenhagen, Denmark, to attend the international conference on climate change, said the Kenyan environmental activist will be formally appointed at a ceremony on Tuesday afternoon in Copenhagen.

In 2004, Maathai, a green advocate, became the first African woman and the first environmentalist, to receive the Nobel Peace Prize for "her contribution to sustainable development, democracy and peace."

The only African woman to win that award so far, Professor Maathai has also served as a government minister, lawmaker, academic and women's rights advocate over the past four decades.

Messengers of Peace are individuals widely recognized for their talents in the arts, academia, sports, entertainment and other fields who work to help raise worldwide awareness of UN ideals and activities.

Through their public appearances, contacts with the international media and humanitarian work, they expand public understanding of how the UN helps to improve the lives of people everywhere.

The other Messengers of Peace and their areas of focus include: conductor Daniel Barenboim (peace and tolerance), actor George Clooney (peacekeeping), author Paulo Coelho (poverty and intercultural dialogue), actor Michael Douglas (disarmament), primatologist Jane Goodall (conservation and environmental issues)and violinist Midori Goto (Millennium Development Goals and Youth).

The other five Messengers are: Princess Haya Bint al Hussein (Millennium Development Goals and hunger), cellist Yo-Yo Ma (youth),actor Charlize Theron (ending violence against women), Nobel Laureate Elie Wiesel (human rights) and singer-songwriter Stevie Wonder (people with disabilities).